/**
 * 3维坐标
 * @author zzhanglin
 */
Vector3D = function(x,y,z) 
{
    this.x = x || 0 ;
    this.y=  y || 0 ;
    this.z=  z || 0 ;
} ;

/**
 * 复制点
 * @returns {Vector3D}
 */
Vector3D.prototype.clone = function ()
{
	return new Vector3D(this.x,this.y,this.z);
};
/**
 * 输出此点的信息
 */
Vector3D.prototype.toString = function()
{
	return "(x=" + this.x + ", y=" + this.y + ", z=" + this.z + ")";	
};